package filter;

import pojo.User;

import javax.servlet.*;
import javax.servlet.annotation.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebFilter(filterName = "LoginFilter",urlPatterns = "/*")
public class LoginFilter implements Filter {
    //进行过滤器的初始化
    public void init(FilterConfig config) throws ServletException {
    }
    //销毁过滤器
    public void destroy() {
    }
    //执行过滤方法
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {
//        chain.doFilter(request, response);
        //检查一下用户是否登录，如果已经登录，那就放行；如果没等登录，就让他去登录
        //将request和response进行类型转换
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        //处理一些特殊情况，比如注册，登录，静态文件都不能拦截
        String [] urls = {"/login.jsp","/register.jsp","/css",
                "/images","/js","/login","/user","/verifyCode" };
        //获取当前访问的uri
        String uri = req.getRequestURI();
        for (String u : urls){
            if (uri.contains(u)){
                //当前访问的是特殊资源
                chain.doFilter(req,resp);
                return;
            }
        }


        //检查session中是否存放了一个LOGIN_USER
        HttpSession session = req.getSession();
        User user = (User) session.getAttribute("LOGIN_USER");
        if (user!=null){
            chain.doFilter(req,resp);
        }else {
            request.setAttribute("LOGIN_MSG","您尚未登录，请先登录！");
            request.getRequestDispatcher("/login.jsp").forward(req,resp);
            return;
        }
    }
}
